The heel is traditionally blocked using padding attached inside the boot upper. For example, the boots described in French Pat. No. 1,006,263 and U.S. Pat. Nos. 2,531,763 and 1,055,295 can be cited. In these boots, paddings are made unitary with the inside slipper of attached thereto with glue, by sewing, soldering, or the like, so that it is not possible to adjust their position precisely according to the morphology of the foot.
Other shoes, such as those disclosed in Swiss Pat. No. 365,972 and French Pat. No. 2,180,315, comprises devices to clamp the heel. These devices enclose the heel from the upper rear part thereof to the lower zone of the malleoli. In these different boots, only the clamping (or pinching) value of the heel can be adjusted by means of a buckle, tightener, or pressurized air pocket.
One can further cite other boots in which heel blocking plates extend on both sides of said heel, bypassing the malleoli, as described in Italian Pat. No. 1,069,934. These blocking plates are associated with the inside slipper by introduction into pockets provided in the latter for this purpose. In the examples set forth in German Pat. No. 2,839,418 and U.S. Pat. No. 2,763,071, the blocking plates can be adjusted by moving them closer to the heel inside the boot, using mechanical systems.
However, all of these devices only have one capability of blocking and/or clamping the heel in the boots, without the possibility of precise adjustment in the vertical plane with respect to the rear protuberance of the calcaneum. Moreover, most of the clamping devices described are inclined to maintain pressure on the heel, tending to push the latter towards the front of the boot, which involves the problem of decreasing the rear support of the base of the leg against the rear part of the upper.